AC3 Audio File Format Description:

Dolby Digital, or AC-3, is the common version containing up to six discrete channels of sound. The most elaborate mode in common usage involves five channels for normal-range speakers (20 Hz – 20,000 Hz) (right front, center, left front, right rear and left rear) and one channel (20 Hz – 120 Hz) for the subwoofer driven low-frequency effects. Mono and stereo modes are also supported. AC-3 supports audio sample-rates up to 48kHz. Batman Returns was the first film to use Dolby Digital technology when it premiered in theaters in Summer 1992. The LaserDisc version of Clear and Present Danger featured the first Home theater Dolby Digital mix in 1995.

Dolby Digital allows a number of different channel selections. The full list of available options is:
Mono (Center only)
2-channel stereo (Left + Right), optionally carrying matrixed Dolby Surround
3-channel stereo (Left, Center, Right)
2-channel stereo with mono surround (Left, Right, Surround)
3-channel stereo with mono surround (Left, Center, Right, Surround)
4-channel quadraphonic (Left, Right, Left Surround, Right Surround)
5-channel surround (Left, Center, Right, Left Surround, Right Surround)

All of these configurations can optionally include the extra Low Frequency Effect (LFE) channel. The last two with stereo surrounds can optionally use Dolby Digital EX matrix encoding to add an extra Rear Surround channel.

Many Dolby Digital decoders are equipped with downmixing functionality to distribute encoded channels to available speakers. This includes such functions as playing surround information through the front speakers if surround speakers are unavailable, and distributing the center channel to left and right if no center speaker is available. When outputting to separate equipment over a 2-channel connection, a Dolby Digital decoder can optionally encode the output using Dolby Surround to preserve surround information.

The '.1' in 5.1, 7.1 etc. refers to the LFE channel, which is also a discrete channel.

Audio Transcoder supports the following conversions with AC3 format files:

• AC3 to AAC
• AC3 to APE
• AC3 to M4A
• AC3 to M4B
• AC3 to MP4
• AC3 to APE
• AC3 to FLAC

• AC3 to MP2
• AC3 to MP3
• AC3 to MPC
• AC3 to OGG
• AC3 to WAV
• AC3 to WMA
• AC3 to SPX

Note that Audio Transcoder is not only a great Audio Converter. It is all-in-one solution to convert any audio files - WAV, WMA, OGG,MP3,MP4, AAC and many others, rip Audio CD's, edit metadata (audio tags) .